Magnetic door latch



Oct. 10, 1961 H. c. wlLsoN 3,003,802

MAGNETIC DOOR LATCH Filed Jan. l5, 1958 United States Patent O 3,003,302. MAGNETIC DOOR LATCH Harry Carl Wilson, 15126 Rayneta Drive,

Sherman Oaks, Calif. FileiiJan. ,13, 195s, ser. No. 708,469 13 Claims. (Cl. 292-2515) This invention relates to latch or keeper devices and more particularly to devices of this type for' use on doors, closures and the like utilizing one or more permanent magnetic elements to retain some movable member such as a door in a desired position.

The strength and -retentive power of modern perma nent magnets has been recognized by prior designers as rendering them suitable for a variety of holding tasks includln'g those of holding doors, drawers and the like in a desired position yet act to release without need for any special operation to disengage the holding means. One such latch device is disclosed in my co-pending application for United States Letters Patent, Serial No. 483,458, led January 24, 1955, and entitled Magnetic latch and method of making the same, now Patent No. 2,906,553 granted September 29, 1959. Magnetic latch devices have served a very useful purpose and are rapidly growing in popularity and scope of use. However, devices of this type as heretofore provided are subject to certain disadvantages, including their high cost due to the number of components, the complexity of the manufacturing and assembling operato'ns, the inability adequately to accommodate themselves to maldns'tallation conditions or disturbed alignment developing after installation, and others.

Recently permanent magnetic elements molded from certain ceramics have become available, and owing to their materially lesser cost of manufacture, these are suitable for use in latch devices. However, such use has not met with the success anticipated because ceramic magnets are subject to shattering under shock and sharply applied loads. Even normal handling in the rapid assembly of components or load applied in locking the components togethers,4 as well as the shock received before and after installation, frequently cause shattering of the magnetic element. Attempts to protect the ceramic elements by riveting, screwing or staking protective members against their opposite sides, although successful to a degree, require considerable skill on the part of workmen and the maintenance of undesirable and costly close manu facture tolerances.

The present invention provides a latch device designed with a view to obviating the shortcomings of prior devices with primary attention being given to the use of a few simple and inexpensive components so designed that manufacture to rough tolerance values is adequate, and capa ble of being assembled quickly by unskilled labor with` out need for tools. Furthermore, installation can be ac complished by the novice using commonly available simple house tools. A further and important feature is the use of a ceramic magnet to hold the detent or keeper plate mounting screw accurately positioned for marking the exact point at which the screw is to be driven, thereby avoiding the need for a skilled mechanic to install the latch. A further feature is the provision of a unique and effective self-aligning device for the keeper which automatically accommodates itself to initial or subsequently occurring conditions tending to prevent the keeper from full and uniform contact with the magnetic retainer, such ICC 2 alignment feature being effective over a wide range of operating conditions.

Accordingly, -a primary object of the invention is the 'provision of an improved magnetic latch device designed for factory assembly Without tools and adapted to be installed by the home ov'ver following the simplest of instructions and bythe use of common household tools.

Another object of the invention is the provision of an improved magnetic latch hyn'g a minimum number of components manufactured to rough tolerances and automatically selfadjustable to accommodate wide-range misalignment between the support for the magnet and the member to which the keeper s attached.

Another object of the inventior'i is the provision of a magnetic latch especially designed to utilize effectively low-'cost ceramic magnets and housed within a casing adapted to be mounted 'within the space provided by the remoya-l of a section of the usual door jamb.

Another object of the invention is the provision of a magnetic latch in which a ceramic permanent magnet is held supported between a pair of protective plates of magnatie material in a selfaligiiig condition by means ef a spring keeper.

Still another object f the invention is 'the provision et a selfaligning' armature detent plate i'es'iliently supported in a self-aligniiig member by a bowed leaf spring'.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to lthe drawing ih which a preferred einbodiment of the invention is illustrated:

Y FIGURE 1 is a fragmentary perspective view of a room door employing the magnetic latch of the present invention to hold the same in closed position;

FIGURE 2 is a fragmentary viev'v partly in sectign and partly in side elevation showing the door in FGURE 1 held closed by the latch device;

FIGURE 3 is a transverse sectional view taken on line 3 3 @f FiGURE 2;

FIGURE 4 is' a view similar te FIGURE' 3y showing the mounting screw supported by the permanent magnet to mark the place forthe mounting of the keeper during installationof the latch device on the door;

FIGUREv 5 is an exploded view showing the position of the partsin readiness for assembly to the casing; and

FIGURE 6 is an exploded View of the armature or keeper assembly prior to assembly to the door.

Referring to FIGURES 5 and v6, there is shown a magnetic latch device having an outer generally rectangular housing 10 preferably formed in one piece of molded plastic or other suitable non-magnetic material. The rear side face of the housing is omitted or open since this face is assembled fiush against awal-l, door casing or other suitable support. The front end. Wall is cut out except for lips 11 and provides air opening through which project the elements' of the loosely mounted magnetic retainer -a'ssembly to be described presently. Molded integral with the inner side lof the front or closed housing' wall 12 is a post 13 having a length equal to the interior width of the housing. 'I he rear corners of the housing are formed with bosses 14, 14 having oval shaped passages 15 for loosely receiving the housing mounting screws 16. The movement allowed by passages 15 permits the casing to be shifted in a manner facilitating the accurate alignment of the magnetic elements enclosed by the casing with the keeper assembly, a feature which will be further described below. The rear face of the housing is also preferably molded with pointed projections 17 ringing the end of passages 15 and adapted to seat in the surface upon which the housing is mounted and cooperating with mounting screws 16 to anchor the casing firmly in a desired position.

The movable magnetic retainer assembly includes a pair of identical plates 20,21 of magnetic material positioned closely against the opposite sides of a rectangular block or wafer 22 of material adapted to be permanently and stronglymagnetized. Although metallic permanent magnetic materials, as for example, alnico, may be used, economies can be realized by employing one of the permanently magnetic ceramic materials commercially available. Each of the protective plates 20, 21 and the magnetic block 22 are provided with similar central openings of considerably greater diameter than post 13 and positioned to be assembled over this post and held in assembled position thereon by a light spring keeper or retainer 25. It will be observed that this keeper is bowed outwardly and provided with a pair of sharp keeper tangs 26 of a size and shape permitting the same to be pressed easily over the end of post 13 but which dig into the side of this post in a manner preventing disassembly therefrom. It will be understood that the dimensions of protective `plates 20, 21 are slightly larger on all sides than magnetic block 22 and that the edges of the protective plates fit loosely within the adjacent side walls of housing 10. The forward ends 24 of plates 20, 21 projectv outwardly through opening 11 of the housing and terminate in a plane spaced slightly outwardly of the housing end Wall. The forward corners 27 of these plates are notched and cooperate with lips 11 of the casing to position accurately the forward ends 24 of plates 20. It is pointed out thatnotched corners 27 and lips 1,1, rather than post 13, carry the principal load stresses imposed when opening a closure, a fact made clear by FIGURE 3.

A feature of construction is the provision of a transverse notch 28 centrally of the forward edge 24 of plates 20, 21, its purpose being to support-the diametric rim edge portions of the head of mounting screwv 30 used to mount the armature or keeper assembly designated generally 31 in FIGURE 6. These notches are employed only during installation of the latch device on a door and serve to mark the point on the closure member at which the screw 30 should be sunk in order to position properly the keeper assembly 31. Further details of this installation operation will be described below.

The armature or keeper assembly 31 is best illustrated in FIGURE 6 wherein it is seen to comprise a magnetic plate 3'2 and a bowed spring aligning plate 33. Plate 32 is flat and provided with a countersunk opening 34 for receiving the body and beveled head of mounting screw 30. Plate 32 is proportioned to bridge the exposed outer ends 24, 24 of magnetic protector plates 20, 21 in the closed position of the door or drawer. The self-aligning `spring plate 33 is formed from spring steel and has inturned pointed ends 35 at its corners adapted to be driven into the surface on which the keeper is mounted in order to anchor it in place and prevent rotation thereof about mounting screw 30. The outwardly bowed center of the spring is provided with a central opening 36 to receive the screw and one end has an up-turned tab 37 extending through an anchoring opening 38 in one end of keeper plate 32 tol lock this plate against rotation about the screw.

One manner of installing the described latch device is illustrated in FIGURES l and 2, the installation environment given by way of example, being a closet door. The flush type closet door 39 controls access to a closet 40. To accommodate the latch housing without the latter protruding door jamb 41 may havea portion removed just wide enough to receive latch casing 1 0. Casing 10 has a depth approximating that of conventional door jambs and a length equal to their usual widths. After the jamb has been notched, the casing is slipped in place and firmly anchored by mounting screws 16. -In the position illustrated in FIGURE Z, the mounting screws are in place but have not been set to anchor the housing in place since preferably this is done as the final installation step.

When the latch housing has been temporarily anchored in the manner described, the head of the keeper mounting screw 30 is seated in notches 28 of the protector plates where it is firmly and rigidly held accurately centered by the magnetic action of magnet 22.` Door 39 is then lightly closed against the pointed end of the screw to mark the place where thescrew should be sunk in the mounting of keeper assembly 31. The hole for the screw is preferably counterbored to avoid cracking or damage to the door, after which it is assembled through openings 34 and 36 of the keeper assembly. It is tightened sutliciently to sink anchor tabs 35 into the door but insufficiently to atten the bowed central portion of the spring. In this manner, plate 32 is held lightly in position and is free to pivot about the bowed center of the spring to the end that its forward face may lie ush `to shift vertically or to pivot about post 13 and it will be recognized that plate 32 is free to pivot to a marked degree about screw head 30. Further alignment is accomplished by dellecting spring back-up plate 33. Once the parts have been properly positioned relative to one another, door 39 is closed against jamb 41 shifting the casing 10 if necessary. Housing mounting screws 16 are then firmly anchored to. seat the anchoring projections 17 `in the wood of door casing 42. This completes the installation of the device and it is ready for normal operation.

So long as keeper plate 32 is in contact with the exposed faces of the magnetic plates 20, 21, it acts to complete the ilux circuit with magnetic block 22 through plates 20, 21 and holds the door rmly and tightly closed. Opening of the door is accomplished by grasping the knob 43' and pulling outwardly away from casing 10. A firm pull readily opens the door without requiring the turning of the knob or any manual operation to release latch parts. Closing of the door is effected simply by pivoting it toward the jamb. As the door approaches nearly to its closed position the magnet will be effective to attract magnetic keeper plate 32 and pull it inwardly to its fully closed position.

During the opening and closing operations, Vit will be understood that the magnetic latch assembly is held resiliently in position on post 13 by spring keeper 25 with all vcomponents being free to shift relative to one another through limited distances in the manner described above. Furthermore, should misalignment of the parts occur during use, and particularly misalignment or shrinkage or warpage of the door or its casing, the components of both the armature assembly and of the magnetic assembly and, in fact, the housing itself, adjust simply and easily to compensate for the changed conditions. All adjustments take place automatically with the exception of the position of casing 10. The position of this element can be shifted by rst loosening mounting screws 16 and then retightening them after the desired adjustment has been made.

While the particular magnetic latch device herein the objects and providing the advantages herenbefore accesos;

stated,- it is to be understood that it is merely illusative of the presently preferred embodiments of theinvention and that no limitations are intended to the details of constrnction or design herein shown other than as defined in the appended claims.

I claim:

l. A magnetic catch comprising a one-piece casing and stud, a permanent magnet sandwiched between a pair of magnetic plates and held loosely and detachably mounted on said stud by a keeper having a press fit over the end thereof, an adjacent pair of said plate ends being exposed along one edge of said casing, and a keeper of magnetic material adapted to bridge the exposed ends of said plates and to be attached to a member for releasable detention by said permanent magnet.

2. A magnetic catch for use in holding a pair of relatively movable members releasably in a predetermined position, said catch comprising a casing of non-metallic material open at one end and along one side face thereof, said casing having an integral stud projecting from the interior surface of the closed face thereof, a sandwich formed by a permanent magnet and at least one magnetic plate loosely mounted over said stud, a spring retainer frictionally secured to the free end of said stud -for holding said magnet and said plate pressed lightly together and against one interior side wall of said casing, and a keeper of magnetic material adapted to be secured to the other of said relatively movable members opposite the end of said magnetic plate facing the open end of said casing whereby said permanent magnet is effective to retain said members together when said keeper abuts the exposed edge of said magnetic plate.

3. A magnetic catch comprising a fiat non-circular molded casing open along one end and one side face, said casing being of non-magnetic plastic material and having a stud formed integral with and projecting from an interior surface of the closed face of said casing, a plurality of wafers fitting loosely over said stud and including a wafer of permanent magnetic material and a wafer of magnetic material having one edge exposed and projecting outwardly beyond the open end of said casing, spring retainer means engaging the outer end of said stud and cooperable therewith to hold said wafers pressed together and against one interior side wall of said casing, and keeper means of magnetic material adapted to be secured to a door or the like in a position to contact the exposed edge of said magnetic wafer when brought into close proximity thereto.

4. A magnetic catch as defined in claim 3 including a keeper having a press fit over the outer end of said stud for holding said wafers against disassembly therefrom and pressed together under slight pressure.

5. A magnetic catch as defined in claim 3 wherein said magnetic keeper means includes a rigid keeper and a thin bowed spring strip, said rigid keeper and spring strip having registering openings centrally thereof to receive fastening means for holding said keeper means resiliently supported on a door with said rigid keeper free for limited tilting movement relative to the underlying crest of said bowed spring as may be necessary to bring the surface of said keeper into parallelism with Ithe exposed edge of said magnetic material as said magnetic catch approaches the closed position thereof.

6. A magnetic catch for doors and the like comprising, a at casing having an open end wall, a ceramic permanent magnet sandwiched between a pair of plates of magnetic material housed within said casing, with adjacent ends of said plates projecting through said open end wall, said plates having a small-area notch centrally of said projecting ends, a keeper of magnetic material for said catch, said notch being sized to seat the head of a screw of magnetic material therein after said casing has been secured to a wall surface close tothe inner side of a door closing toward the pointed end of said screw whereby said screw provides a pointed marker for marking the door for the attachment ofthe keeper with assurance that the keeper will -be mounted with its center accurately aligned with the center of the notched area of said plates.

7. A magnetic ctc'h as defined in claim 6 including means for holding said plates assembled against the opposite faces of said ceramic magnet while allowing limited relative movement therebetween as necessary to bring the surface' f said keeper into parallelism with the surface ofthe projecting 'ends of said magnetic plates immediately prior to these surfaces contacting oneanother as said magnetic keeper closes.

8. A magnetic catch as defined in claim 7 wherein said keeper includes an underlying spring surrounding the mounting screw .for said keeper, the underside of said keeper and the portion of said spring in contact therewith being formed to provide limited universal movement therebetween as necessary to bring the outer surface of said keeper into parallelism with the notched end of said plates of magnetic material as the latter approach contact with said keeper.

9. A magnetic catch having a casing adapted to be mounted with one end face substantially flush with the door-contacting edge of a door jamb, said casing housing a permanent magnet positioned between a pair of magnetic plates protruding slightly beyond the edges of said magnet with one end edge of each projecting through an opening in said casing facing the door surface, a keeper of magnetic material adapted to be secured to the door surface in a position to abut the projecting edges of said plates, and means resiliently holding said keeper in a previous accurately adjusted position in which the surface of said keeper was in parallelism with the projecting edges of said plates immediately prior to actual contact therewith thereby assuring maximum and uniform holding power for each catch installation.

10. A magnetic catch as defined in claim 9 in which said cas'ing has integral therewith a plurality of groups of very small pointed elements adapted to penetrate the surface to which said casing is attached thereby holding the same against displacement from adesired installed position, the smallness and number of said pointed elements permitting said catch to be remounted several times in the same area without sacrifice in the anchoring effectiveness of said elements.

ll. A casing for use as a housing for a magnetic catch, said casing being formed from a :single piece of plastic material, said casing being generally rectangular with an open face and an open end, an integral stud projecting from the inner side of the closed face of said casing, and a pair of bosses interiorly of said casing and integral therewith provided with openings therethrough to receive a pair of mounting screws to clamp the open face of said casing to a wall sur-face.

l2. A casing as defined in claim ll wherein the open side of said casing has a group of very small pointed eicments projecting therefrom and surrounding one end of each screw receiving opening and to lbe pressed into a wall surface as the mounting screws are driven home, said pointed elements cooperating with said screws in anchoring said casing against displacement relative to a mounting wall surface, and the small size and arrangement of said elements being such as to permit remounting of said casing in closely spaced positions without difficulty or sacrifice in the anchoring effectiveness of said elements.

13. A casing as defined in claim ll wherein said screw openings are wider in one direction than in another to permit limited relative movement thereof as the mounting screws are being tightened, and a group of very small wall penetrating tangs at the wall contacting ends of each of said bosses adapted to be pressed into the wall as the screws are tightened.

(References on following page) 7 References Cited in the` file of this patent UNITED STATES PATENTS Hage Feb. 20, 1923 Ventura Aug. 3, 1937 Bernhard July 11, 1950 Vasquez Sept. 12, 1950 Borchers et al Nov. 16, 1954 Schmitt Feb. 1, 1955 Teetor Sept. 27, 1955 8 i Saxton May 14; 1957 Loeb June 3, 1958 Curtiss et al. Mar. 10, 1959 Martin July 28, 1959 Heppner May 3, 1960 Duhm July 5, 1960 FOREIGN PATENTS Great Britain Aug. 26, 1948 

